Methylhydrazine → Ethyl 3-difluoromethyl-1-methyl-4-pyrazole carboxylate

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Reaction Steps

10.8 g of N-1,1,2,2-tetrafluoroethyldimethylamine were initially charged in 50 ml of acetonitrile under argon and 26 g of boron trifluoride as a 17% solution in CH3CN were added at RT. The mixture was stirred for 30 min and then admixed with 8.67 g of ethyl dimethylaminoacrylate. The mixture was stirred at RT for 2 h and then added slowly to the solution of 3.4 g of methylhydrazine in 10 ml of acetonitrile at 10° C. After stirring at RT for 2 h, the acetonitrile was removed completely under reduced pressure and the product was admixed with water and filtered off. Distillation under reduced pressure or washing with cyclohexane afforded 10 g of the product with the purity of 99% and an m.p. of 62-63° C.

Provenance & Evidence